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Improving the representation of Arctic sea salt aerosols in climate models using observations from field campaigns and remote sensing

Active Dates 8/1/2022-7/31/2025
Program Area Atmospheric System Research
Project Description
Polar regions, especially the Arctic, are particularly sensitive to climate change. Aerosol particles in the atmosphere can alter the surface energy balance and climate in polar regions by forming clouds that trap Earth’s outgoing radiation, leading to warming, or reflecting sunlight away, leading to cooling. Sea salt aerosols, or particles containing salts originating from the ocean, are a major contributor to total aerosol in the Arctic. The dominant sources of sea salt aerosol in the Arctic during the cold season, when concentrations are at their peak, are still under debate. 

Cracks in sea ice (“leads”) through which sea spray can release salt have been identified as a source of sea salt aerosols in the Arctic since the early 1970s. Recent observations suggest they may in fact be a leading source of Arctic sea salt aerosols in the cold season. This source is currently missing from climate models, leading to potentially large biases in simulations of Arctic aerosols, clouds, and radiation and a critical gap in our understanding of future Arctic climate change. Ongoing summertime sea ice loss and changes in sea ice properties will likely increase the frequency of Arctic sea ice leads and their aerosol emissions, with potential feedbacks on the climate system that must be quantified.

The recently completed Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) mission provides new and unprecedented observations of linkages between Arctic sea ice, aerosols, and clouds. These, in combination with additional recent Department of Energy Atmospheric Radiation Measurement (ARM) campaigns in the Arctic spanning the cold season, will allow us to investigate and model the impacts of sea salt aerosol particles emitted from sea ice leads on climate for the first time. Specifically, we will (i) assess the impacts of sea salt aerosol emissions from sea ice leads on present-day Arctic aerosols, clouds, and radiation; (ii) improve the representation of Arctic aerosols and climate in Earth system models by incorporating sea salt aerosol emissions from leads.  

To do so, first we will analyze observed sea ice, aerosol, cloud, and radiation properties from the recent ARM campaigns and station observations in the Arctic, in combination with satellite observations of leads. We will then implement a new parameterization of sea salt aerosol emissions from leads into the Energy Exascale Earth System Model (E3SM), constraining key uncertainties in the emissions against the ARM observations. We will perform and analyze results from E3SM simulations that include additional sea salt aerosol emissions from leads in present and future climates, to better understand feedbacks between sea ice, aerosols, clouds, and climate, and predict how future climate change will influence the sea ice-atmosphere system.
Award Recipient(s)
  • University of Illinois Urbana-Champaign (PI: Horowitz, Hannah)